I have a Sukhoi and I balanced it with an OS 160 in the nose. I placed the servos on the plane in their correct locations and found it to be tail heavy with the elevator and rudder servos in the tail. It was still tail heavy with the rudder servo up front. I decided to mount all three servos on the servo tray under the CG. This allowed me to get the balance right.

I used a Dubro Pull-pull for the rudder and Dave Brown Fiberglass pushrods for the elevator halves (2 servos). I am not liking this setup because I had to put a slight bend in the wire on the end of the rods where they exit the fuseage. This bend is causing some flexing. I am using 4-40 wires.

I was thinking of cris-crossing the rods in the tail to the left servo controlled the right elevator and vise-versa.

Has anybody tried this?

Erick

I did the same thing you did. However, I find that the Creek planes fly better a little tail heavy. The instruction calls for 30% balance, but I think it flies better at 33%. The Creek planes have thicker airfoil at the tip (13%) than the root (12%), so it will not tip stall too bad. At 33% CG balance, it will not stall in a moderate speed turn; it will only stall when it's too slow on the landing flare, like 10 mph; even then, it's a gentle stall that's recoverable in 5 ft vertically.

You can start by having the elevator servos up front, and gradually add tail weight to see how the plane responds. If it flies fine at the aft balance, then move the servos to the back.

Yes, I hated it when the elevator servos were up front. I had 2" x 0.5" cut out for the pushrod because they move so dang much at the passthrough.

I built a H9 EDGE for a friend and did the Dave Brown thing with 440 hardware but it still had a lot of slop. It seems to fly well so I may do the same thing with the Creek Hobbies Extra that I'm building.

"I was thinking of cris-crossing the rods in the tail to the left servo controlled the right elevator and vise-versa. "

I've got a Direct Connection Ultimate (bought used) and it was setup with the cris-crossing as you mentioned but still a lot of slop. But it flys well.

I've been thinking of trying pull-pull on the elivator and rudder.

ADVANTAGE: only one servo for the elivator and one for the rudder; no slop; no servos in the tail.

DISADVANTAGE: I haven't figured out how to run the cables and where to cut the exit holes

ABOVE: When I say "flys well" I'm talking about sport flying and simple aerobatics. NOT 3D.

It would be IDEAL not to have to add any weight.

Seanychen & Eric Boyer

I've put together the same package (OS 1.60 & Creek Hobbies Sukhoi) and was planning on rear-mounting the servos. I want a rock-solid connection between control surfaces and servos, no slop.... How far is the CG off by? Any chance you can move the engine more forward on its rails. I could also mount the battery and RX up against the fuel tank (or below it).

Would I be better off mounting the Moki 180 I have on the Sukhoi and use the OS 1.60 for the Hanger 9 Cap 232?

Ummm, The H9 Cap 73" has a worse tail heavy problem than the Creek planes. I actually crashed my H9 Cap due to tail-heaviness right after I moved the elevator servos rear; it flew great with the servos up front. Also, the H9 Cap is heavier, thus needs the Moki power.

Regarding the Creek planes: they are more docile even when they are tail heavy, compared to the H9 Cap. So if you can get the CG at 33% at center-of-lift, you should be fine.

I had forgotten that that was the reason I got the Moki in the first place. I had a used Cap in the past and the previous owner had an ST-2300, close to the OS FX in weight, on it. He had more than a half pound of weight in the nose. I put an ST-3000, close to the Moki in weight, on it and ended up with a nose-heavy airplane, even after removing the half pound of weight. I calculated that the forward position of the 4 servos, when moved to their normal mid-deck position will bring the plane almost to good CG with the Moki on the nose. Thanks for reminding me.

Back to my original question: If I install the servos in the tail of the Sukhoi and mount the OS FX 1.60 in the nose where is my CG going to be and how much, if any, weight will it need to correct?

I have elevator servos at tail and rudder servo up front. It balances at 33% behind LE at center-of-lift chord. If you have all 3 servos back there, it might be worse, like 34%.

if you want to run pull pull on the rear surfaces take a look at the dp bipe as thats the way dp shows it in my manual. i also set mine up with pull pull on those 2 surfaces The DAve patrick Bipe)

i have the creek extra that i will run 2 elevators servos and run the rudder on a pull pull with the fuel tank o the cg with a perry pump vp-30.

The hanger 9 caps have the 3 servos set up under the wing if you need to look at one of those set up that was built according to the manual if you have access to one of those babies.